watchOS 5.0 (build 16R5283r) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2018-06-11T17:07:00Z. The update package is 563.04 MB. This is a delta (partial) update that requires 4.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 57f3d3ee155dc24cfbe0194521bb106ba600d647.zip.